Several books deal with Sobolev spaces on open subsets of R (n), but
none yet with Sobolev spaces on Riemannian manifolds, despite the fact
that the theory of Sobolev spaces on Riemannian manifolds already goes
back about 20 years. The book of Emmanuel Hebey will fill this gap, and
become a necessary reading for all using Sobolev spaces on Riemannian
manifolds.
Hebey's presentation is very detailed, and includes the most recent
developments due mainly to the author himself and to Hebey-Vaugon. He
makes numerous things more precise, and discusses the hypotheses to test
whether they can be weakened, and also presents new results.